KR102329370B1 - Piezoelectric jetting system with quick release jetting valve - Google Patents

Abstract

Disclosed is an injection dispenser comprising an actuator housing, an actuator, a fluid body housing, and a fluid body. The actuator is located in the actuator housing, and the fluid body housing is coupled to the actuator housing. The fluid body includes a fluid inlet coupled to the fluid body housing and in communication with the fluid bore. The fluid body further includes an injection valve having a movable shaft operatively coupled to the actuator when the fluid body housing is coupled to the actuator housing. The shaft is moved by the actuator housing to eject an amount of fluid from the fluid bore. The fluid body may be removed from the fluid body housing when the fluid body housing is separated from the actuator housing.

Description

PIEZOELECTRIC JETTING SYSTEM WITH QUICK RELEASE JETTING VALVE

Cross-referencing of related applications

This application claims priority to U.S. Provisional Patent Application No. 62/165,245, filed on May 22, 2015, the entire contents of which are incorporated herein by reference.

The present invention relates to a non-contact jet dispenser for depositing small droplets of a viscous fluid onto a substrate, and in particular to a dispenser of this type actuated by one or more piezoelectric elements.

Non-contact viscous material dispensers are sometimes used to apply a minimal amount of viscous material onto a substrate, for example, the viscous material having a viscosity greater than 50 centipoise. For example, contactless viscous substance dispensers are used to apply various viscous substances onto electronic substrates such as printed circuit boards. The viscous material applied to the electronic substrate is by way of example and not limitation, universal adhesives, UV curing adhesives, solder pastes, solder fluxes, solder masks, thermal greases, lid sealants, oils, encapsulants, potting compounds. (potting compounds), epoxies, die attach fluids, silicones, RTVs, and cyanoacrylates.

The specific applications for dispensing viscous material from a non-contact jetting dispenser onto a substrate are numerous. In semiconductor package assembly, among other uses, underfilling, solder ball reinforcement in ball grid arrays, dam and fill operations, chip encapsulation, underfill chip scale packaging, cavity fill distribution, die attach distribution, lid seal distribution, Applications exist for flow-free underfilling, flux spraying, and dispensing thermal compounds. For surface mount technology (SMT) printed circuit board (PCB) fabrication, surface mount adhesive, solder paste, conductive adhesive, and solder mask materials can be dispensed from non-contact dispensers as well as selective flux jetting. Conformal coatings may also be selectively applied using a non-contact dispenser. In general, the cured viscous material protects the printed circuit board and the devices mounted thereon from harmful substances originating from environmental stresses such as moisture, mold, dust, corrosion and abrasiveness. The cured viscous material may also preserve electrical and/or thermal conductivity properties in certain uncoated areas. There are also applications in the disk drive industry, life science applications for medical electronics, and general industrial applications for bonding, sealing, forming gaskets, painting and lubrication.

Dispensing dispensers may have pneumatic or electric actuators for dispensing droplets of viscous material from an outlet orifice of the dispenser while moving a shaft or tappet repeatedly towards the seat generally. Electrically actuated jet distributors may in particular use piezoelectric actuators.

The ability to clean the injection distributor valve is critical to valve performance. To achieve proper cleaning, the fluid path to and within the valve must be readily accessible. Many spray dispenser designs still do not have adequate access to adequately clean all required surfaces. Some materials, such as UV curable materials, will cure in the fluid path due to the heat applied by the heating element associated with the dispenser. Occasionally, the user must disassemble the heating element in some form to gain access for cleaning purposes. This requires time and additional tools.

For at least this reason, there is a need to provide an injection system and method that addresses these and other problems.

FIELD OF THE INVENTION The present invention relates generally to an actuator housing, an actuator, a fluid body housing, and a jet dispenser comprising a fluid body. The actuator is located in the actuator housing, the fluid body housing being coupled to and separate from the actuator housing. The fluid body comprises a fluid inlet coupled to the fluid body housing and communicating with the fluid bore. The fluid body comprises an injection valve having a movable shaft operatively coupled to the actuator when the fluid body housing is coupled to the actuator housing. It further comprises.Shaft is actuated by actuator to eject an amount of fluid from fluid bore.Fluid body can be removed from fluid body housing when fluid body housing is separated from actuator housing.This is easy to clean and/or or to enable replacement.

In another aspect, the actuator can further include a piezoelectric unit that extends a first distance in response to an applied voltage, and an amplifier operatively coupled to the piezoelectric unit. The fluid body housing may be coupled to the actuator housing with a hinge, and the fluid body housing may be pivoted between a position in which the fluid body housing is coupled to the actuator housing and a position in which the fluid body housing is disengaged from the actuator housing. In this way, the fluid body housing can be easily moved between engaged and disengaged positions without completely disengaging from the actuator housing and from the fluid body housing. However, the fluid body housing may be coupled to the actuator housing in any suitable manner, including any manner that results in complete separation of the fluid body housing from the actuator housing.

In another aspect, the jet distributor may be coupled to the actuator housing by a rotating connector. The fluid body housing may further include a hook-shaped flange, and the rotatable connector may engage the hook-shaped flange to engage the actuator housing and the fluid body housing. Further, the connector housing may be rigidly attached to the actuator housing, and the rotating shaft includes the rotating connector and is seated within the connector housing.

In yet another aspect, the jet distributor may be coupled to the actuator with a moveable pin. The movable pin may engage the fluid body housing and the actuator housing by moving within a slot in the fluid body housing. Additionally, the connector housing may be rigidly attached to the actuator housing and may include a spring biasing element. The moveable pin may move against the spring biasing element towards the actuator housing to engage or disengage the fluid body housing and the actuator housing.

In another aspect, the actuator housing can include a bore and the fluid body can include a tappet assembly that includes an injection valve. The tappet assembly may be retained in the bore of the actuator housing when the actuator housing and the fluid body housing are engaged. Further, the tappet assembly may be removable from the fluid body.

In yet another aspect, the fluid body housing may be configured with a T-shaped groove to provide a path for fluid leakage.

Various additional features and advantages of the present invention will become more apparent to those skilled in the art upon review of the following detailed description of exemplary embodiments taken in conjunction with the accompanying drawings.

1 is a perspective view of a spray dispenser system in accordance with an exemplary embodiment of the present invention;
Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1;
Fig. 2a is an enlarged cross-sectional view of the tappet assembly and fluid body taken from Fig. 2, showing the tappet in an open position;
Fig. 2B is a cross-sectional view similar to Fig. 2A, but showing the closed tappet after ejecting a droplet of fluid;
3 is a partially exploded perspective view of the piezoelectric actuator of the distributor;
Fig. 4 is a perspective view of a piezoelectric spray dispenser with specific elements shown in dashed lines to better show internal details;
Fig. 5 is a side view of the lower part of the actuator showing the lever amplification mechanism;
6A is an enlarged schematic view of a fluid body housing coupled to an actuator housing;
Fig. 6B is a view similar to Fig. 6A, but showing the connector rotated such that the fluid body housing can be disengaged from the actuator housing;
Fig. 7 is a perspective view of the fluid body housing separated from the actuator housing and the fluid body removed;
Fig. 8 is a perspective view of an alternative embodiment of a connector that allows coupling and disengagement of the fluid body housing relative to the actuator housing;
Fig. 8A is a cross-sectional view taken along line 8A-8A of Fig. 8;

1 to 4 , a spraying system 10 according to the present invention comprises a spraying distributor 12 associated with a main electronic control 14 . The jet distributor 12 includes a fluid body 16 coupled to an actuator housing 18 . In particular, the fluid body 16 is held within a fluid body housing 19 which may contain one or more heaters (not shown) depending on the needs of the application. The fluid body 16 receives fluid under pressure from a suitable fluid supply 20, such as a syringe barrel (not shown). A tappet or valve assembly 22 is coupled to the housing 18 and extends into the fluid body 16 . A mechanical amplifier (eg, lever 24 ) is coupled between the piezoelectric actuator 26 and the tappet or valve assembly 22 , as described below.

For the purpose of cooling the piezoelectric actuator 26 , air may be introduced into the inlet port 28 from the source 27 and exhausted from the exhaust port 30 . Alternatively, depending on the cooling demand, both ports 28 , 30 may receive cooling air from the source 27 as shown in FIG. 2 . In this case, one or more other exhaust ports (not shown) will be provided in the housing 18 . The temperature and cycle control 36 controls one or more heaters (not shown) possessed by the distributor 12 to control the actuator 26 during the injection operation and to maintain the dispensed fluid at a desired temperature. provided for As another option, this control 35 , or other control unit, may control the cooling demand of the actuator 26 in a closed loop manner. As also shown in FIG. 4 , the piezoelectric actuator 26 further includes a stack 40 of piezoelectric elements. This stack 40 is held in compression by respective flat compression spring elements 42 , 44 coupled to opposite sides of the stack 40 , respectively. In particular, upper and lower pins 46 , 48 are provided and hold the flat spring elements 42 , 44 with respect to each other by means of a stack 40 of piezoelectric elements therebetween. The upper fin 46 is held within the upper actuator portion 26a of the actuator 26 , while the lower fin 48 directly or indirectly engages the lower end of the stack 40 . The upper actuator portion 26a securely receives the stack 40 of piezoelectric elements, such that the stack 40 is stabilized against any lateral movement. In this embodiment, the lower pin 48 is coupled to the lower actuator portion 26b, in particular the mechanical armature 50 ( FIG. 2 ).

The upper surface 50a of the mechanical armature 50 rests against the lower end of the piezoelectric stack 40 . Spring elements 42 , 44 stretch between pins 46 , 48 so that springs 42 , 44 apply a constant compression against stack 40 as shown by arrows 53 in FIG. 4 . do. The flat spring elements 42 , 44 may in particular be formed in a wire EDM process. The upper end of the piezoelectric element stack 40 is held against the inner surface of the upper actuator portion 26a. Therefore, the upper pin 46 is stationary while the lower pin 48 is floating or moving by the springs 42 , 44 and by the mechanical armature 50 as described herein.

When a voltage is applied to the piezoelectric stack 40 , the stack 40 expands or stretches, which moves the armature 50 down against the force of the spring elements 42 , 44 . Stack 40 will change length proportional to the amount of voltage applied.

As shown in FIG. 2 , a mechanical armature 50 is, in this embodiment, coupled to the armature 50 generally proximate a first end 24a and coupled to a push rod 68 at a second end 24b. It is operatively coupled to a mechanical amplifier configured as a lever 24 . The lever 24 is integrally formed from the lower actuator portion 26b, for example, via an EDM process that also forms a series of slots 56 between the mechanical armature 50 and the lever 24. As will be further described below, a lever 24 or other type of mechanical amplifier amplifies the distance that the stack 40 extends or stretches by the required amount. For example, in this embodiment, the downward movement of the stack 40 and mechanical armature 50 is amplified by about 8 times at the second end 24b of the lever 24 .

Referring now to FIGS. 2 , 2A , 2B and 5 , the flexure 60 couples the lever 24 to the mechanical armature 50 . As best shown in FIG. 5 , the lever 24 pivots about a pivot point 62 that is at approximately the same horizontal level as the second end 24b of the lever 24 . This position of the pivot point 62 serves to minimize the effect of the arc, and the lever 24 rotates through the arc. A series of slots 56 are formed in the lower actuator portion 26b forming the bend 60 . When the piezoelectric stack 40 is stretched under application of voltage by the main control 14 as shown by arrow 66 in FIG. 5 , the lever 24 causes the stack 40 to move over the mechanical armature 50 . As it is pushed down, it rotates generally clockwise about pivot point 62 . A slight rotation of the lever 24 occurs against the elastic bias applied to the flexure 60 . As the second end 24b rotates slightly clockwise about the pivot point 62 , the second end moves down and likewise an attached push rod 68 as shown by arrow 67 in FIG. 5 . ) down (Fig. 2).

The second end 24b of the lever 24 is secured to the push rod 68 using suitable screw fasteners 70 , 72 . The push rod 68 runs within the guide bushing 74 and rests against the upper head portion 76a of the tappet or valve element 76 associated with the tappet or valve assembly 22 . The guide bushing 74 is held in the housing 18 by pins 75 as best shown in FIGS. 2A and 2B . The assembly of the push rod 68, guide bushing 74, and pin 75 allows some "give" to ensure proper movement of the push rod 68 during operation. In addition, the push rod 68 is made of a material that bends slightly laterally in an elastic manner during its reciprocating movement by the tappet or valve assembly 22 and lever 24. The tappet assembly uses an annular element 80 to form the lower portion of the housing 18. It further includes a coil spring 78 mounted therein. The tappet or valve assembly 22 further includes an insert 82 retained in the fluid body 16 by an O-ring 84. Annular element 80 and insert 82 comprise an integral element, i.e., the cartridge body in this embodiment, Cross-drilled weep holes 85 are any that leak past O-ring 86. to permit the escape of the liquid of the spring 78. An additional o-ring 86 is provided with a tappet or Seals valve element 76. Fluid is supplied from fluid supply 20 to fluid bore 88 through inlet 90 and passageways 92, 94 of fluid body 16. O-ring 84 ) seals the exterior of the cartridge body formed by the insert 82 and the annular element 80 from the pressurized fluid in the bore 88 and passageway 94. The fluid passageways 92 and 94 are provided in the fluid body 16. It is sealed by a plug member 96 that is threaded to the plug member 96. The plug member 96 may be removed to allow access for cleaning the inner passageway 94.

The operation of the system 10 for dispensing droplets or small amounts of fluid will be best understood by examining FIGS. 2-4 in conjunction with FIGS. 2A and 2B . 2A shows the tappet or valve element 76 raised to an open state when the voltage across the piezoelectric stack 40 has been sufficiently removed. This causes the stack 40 to shrink. As stack 40 retracts, flat springs 42 , 44 pull armature 50 upward, which raises second end 24b of lever 24 , and also raises push rod 68 . make it Thus, the coil spring 78 of the tappet or valve assembly 22 urges the upper head portion 76a of the tappet or valve element 76 upward and releases the tappet or valve element from the valve seat 100 secured to the fluid body 16 . The distal end 76b of the valve element 76 is raised. In this position, the fluid bore 88 and the area below the distal end 76b of the tappet or valve element 76 are filled with additional fluid to “load” the spray dispenser 12 and spray for the next injection cycle. Prepare the dispenser (12).

When the piezoelectric stack 40 is activated, i.e., when a voltage is applied to the piezoelectric stack 40 by the main electronic control 14 (FIG. 1), the stack 40 expands and pushes towards the mechanical armature 50. . This rotates the lever 24 clockwise and moves the second end 24b down, and also moves the push rod 68 down. The lower head portion 68a of the push rod 68 is pushed down on the upper head portion 76a of the tappet or valve element 76 as shown in FIG. 2B , the tappet or valve element 76 having its distal end ( 76b moves rapidly down against the force of the coil spring 78 until it engages against the valve seat 100 . In the process of movement, the distal end 76b of the tappet or valve element 76 forces a droplet 102 of fluid from the discharge outlet 104 . The voltage is then removed from the piezoelectric stack 40 , which reverses the motion of each of these components to raise the tappet or valve element 76 for the next injection cycle.

It will be appreciated that a piezoelectric actuator 26 could be used conversely to eject a droplet. In this case, the various mechanical actuation structures, including levers 24 or other types of mechanical amplifiers, are designed differently so that when voltage is removed from the piezoelectric stack 40, the resulting contraction of the stack 40 is the will cause movement of the tappet or valve element 76 towards the valve seat 100 and the discharge outlet 104 to eject the droplet 102 . Then, upon application of voltage to the stack 40 , the amplification system and other actuating components engage the tappet or valve element 76 to load additional fluid into the fluid bore 88 for the next injection operation. will elevate In this embodiment, the tappet or valve element 76 is normally closed, ie, engages the valve seat 100 when there is no voltage applied to the piezoelectric stack 40 .

As also shown in FIG. 2 , the upper actuator portion 26a is separated from the lower actuator portion 26b , each of these portions 26a , 26b being formed of a different material. In particular, the upper actuator portion 26a is formed of a material having a lower coefficient of thermal expansion than the material forming the lower actuator portion 26b. Each actuator portion 26a, 26b is rigidly fastened to one another using screw fasteners (not shown) extending from the lower actuator portion 26b to the upper actuator portion 26a. The assembly of upper and lower actuator portions 26a , 26b is then fastened to the housing by means of a number of bolts 110 . In particular, the lower actuator portion 26b may be formed of PH17-4 stainless steel, whereas the upper actuator portion 26a may be formed of a nickel-iron alloy such as Invar. 17-4 PH stainless steel has a very high durability limit, or fatigue strength, which increases the life of the bend 60 . The thermal expansion coefficient of this stainless steel is about 10 μm/m-C, whereas that of Invar is about 1 μm/m-C. The ratio of thermal expansion of such materials may be higher or lower than about 10:1. The coefficients of thermal expansion associated with the upper and lower actuator portions 26a, 26b effectively provide eccentricity with respect to each other. The different coefficients of thermal expansion of the upper and lower actuator portions 26a, 26b enable the actuator 26 to operate consistently over a wide temperature range. Also, when operating with high impact coefficients, piezoelectric stacks generate significant heat. The use of the invar provides a more absolute positioning of the end of the actuator 26, and therefore a more accurate and usable stroke.

Referring now to FIGS. 6A, 6B and 7 in conjunction with FIGS. 1 and 1 , the fluid body housing 19 serves to hold the fluid body 16 in the position shown in FIG. 2 . In this regard, FIGS. 2 and 6A show the fluid body housing 19 coupled to the actuator housing 18 by a hinge 122 at one end and a rotary connector 124a proximate to the opposite end. The rotary connector 124a connects and disconnects with the hook-shaped flange 126a on the fluid body housing 19 . Rotational connector 124a is a portion of a rotational shaft 124 or cam-lock that extends within connector housing 127 . The rotating shaft 124 has, at its opposite end, the same connector (not shown) that engages and disconnects the other hook-shaped flanges 126b when the rotating shaft 124 is rotated as described below. To lock the rotary shaft 124 in the engaged or locked position, a set screw 128 is screwed into a friction fit with the groove 129 (FIG. 2). The groove 129 maintains the axial position of the rotation shaft 124 . The connector housing 127 is rigidly attached to the actuator housing 18 . When the fluid body 16 is secured to the fluid body housing 19 , the tappet or valve assembly 22 is retained in the bore 130 of the actuator housing 18 as shown ( FIGS. 2A and 2B ). Additional passageways 131 , 132 , 133 are provided in actuator housing 18 and fluid body housing 19 to allow provision of, for example, wiring, one or more temperature sensors and one or more heaters (not shown). One or more heating elements (not shown) may be positioned directly within the fluid body housing 19 for the purpose of heating the fluid therein. These heating elements do not need to be removed or otherwise handled when the fluid body housing 19 is removed from the actuator housing 18 for maintenance and/or other service.

6A and 6B, the rotation shaft 124 separates the fluid body housing 19 from the position where the fluid body housing 19 is rigidly attached to the actuator housing 18 (Fig. 6A). The fluid body housing 19 may be rotated between a position ( FIG. 7 ) where it may be rotated down about the hinge 122 to do so. A tool (not shown) engages a hexagonal shaped bore 134 to rotate the axis of rotation between the positions shown in FIGS. 6A and 6B . Once separated, the fluid body 16 can be removed from the fluid body housing 19 as also shown in FIG. 7 . The upper surface of the fluid body housing 19 includes a T-shaped groove 140 that provides a path for any fluid leakage or overpressure conditions. Fluid leakage through the O-rings 84 and/or 86 may be vented out from the T-shaped groove 140 . 2 and 7 , removal of the fluid body 16 allows for easy cleaning and/or other maintenance of components before the fluid body 16 is reinserted within the fluid body housing 19 . will make it possible In this regard, the tappet or valve assembly 22 may also be easily removed from the fluid body and replaced with one or more new parts and/or ones cleaned for reuse. Also, passages 92 and 94 can be easily cleaned. The passageway 92 can be easily cleaned when the fluid body 16 is removed, while the passageway 94 can be easily cleaned when the plug member 96 is removed.

8 and 8A show an alternative embodiment for a connector used to couple a fluid body housing 19 to an actuator housing 18 . In this embodiment, the moveable pin 150 is coupled to the connector housing 127 of the actuator housing 18 . This pin 150 can be moved back and forth within the pair of slots 151a, 151b in the direction of the double-headed arrow 152 of FIG. 8 against the bias of the pair of springs 154 (FIG. 8A). ). Thus, the pin 150 is positioned against the bias of the springs 154 to allow the fluid body housing 19 to pivot downward to disengage the fluid body housing 19 from the actuator housing 18 . ) to enable maintenance and/or replacement of the fluid body 16 as described above. When the fluid body 16 is replaced in the fluid body housing 19 , the assembly of the fluid body 16 and the fluid body housing 19 then rotates upward, and the cam surface 160 of the fluid body housing 19 . They urge the pin 150 towards the actuator housing 18 against the bias of the springs 154 . When the fluid body housing 19 reaches the position shown in FIG. 8 , the spring biasing pin 150 moves away from the actuator housing 18 due to the biasing force of the springs 154 and the slots 151a, 151b Snap-fits into This locks the fluid body 16 in the position shown in FIG. 2 for the purpose of operating as a jet dispenser.

While the present invention has been illustrated through the description of specific embodiments and while the embodiments have been described in considerable detail, there is no intention to limit the scope of the appended claims to such details. The various features described herein can be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. Accordingly, the present invention is not limited to the specific details, representative devices and methods and illustrative examples, which have been shown and described in broad terms. Accordingly, the beginning of changes may be made from these details without departing from the scope or spirit of the general inventive concept.

Claims (12)

A spray dispenser comprising:
actuator housing,
an actuator in the actuator housing;
a fluid body housing coupled to the actuator housing with a hinge at one end, wherein at an opposite end, the fluid body housing is pivotable between a position in which the fluid body housing is coupled to the actuator housing and a position in which the fluid body housing is disengaged from the actuator housing; the fluid body housing, and
a fluid body coupled to the fluid body housing and including a fluid inlet and an injection valve in communication with the fluid bore;
the injection valve includes a movable shaft operatively coupled with the actuator when the fluid body housing is coupled to the actuator housing, the movable shaft being moved by the actuator to eject an amount of fluid from the fluid bore , wherein the fluid body is removable from the fluid body housing when the fluid body housing is separated from the actuator housing. 5. The dispenser of claim 1, wherein the actuator further comprises a piezoelectric unit extending a first distance in response to an applied voltage, and an amplifier operatively coupled to the piezoelectric unit. delete 2. The dispenser of claim 1, wherein said fluid body housing is coupled to said actuator housing at said opposite end by a rotatable connector. 5. The dispenser of claim 4, wherein said fluid body housing further comprises a hook-shaped flange, said rotatable connector engaging said hook-shaped flange to engage said actuator housing and said fluid body housing at said opposite end. 6. The spray dispenser of claim 5, wherein a connector housing is rigidly attached to the actuator housing, and a rotational axis includes the rotation connector and is seated within the connector housing. 2. The dispenser of claim 1, wherein said fluid body housing is coupled to said actuator housing at said opposite end by a moveable pin. 8. The dispenser of claim 7, wherein the moveable pin engages the fluid body housing and the actuator housing by moving within a slot in the fluid body housing. 9. The connector housing of claim 8, wherein the connector housing is rigidly attached to the actuator housing and includes a spring biasing element, the moveable pin engaging the spring biasing element to engage or disengage the fluid body housing and the actuator housing at the opposite end. A jet distributor moving against the actuator housing. 2. The actuator of claim 1, wherein the actuator housing comprises a bore and the fluid body comprises a tappet assembly comprising an injection valve, the tappet assembly comprising: Spray distributor retained in bore. 11. The dispenser of claim 10, wherein said tappet assembly is removable from said body of fluid. The dispense dispenser of claim 1 , wherein the fluid body housing is configured with a T-shaped groove to provide a path for fluid leakage.

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